Mechanical telephone



. (-'No Model.) l

T. H. WEINHAUS.

MECHANICAL TELEPHONE.

N0. 355,363. Patented Jan. 4, 1887.

Inv@ 71' n percus Pv W. um n. z:4

UNITED `STATES PATENT OFFICE,

THEODOR Il. VVEINHAUS, OF T. CLOUD, MINNESOTA.

MECHANICAL TELEPHONE.

SECIFECATION forming part of Letters Patent No. 355,363, dated January l, 1887.

(No model.)

.To .cli/,wacht zit may concern:

Be 'it known 'that I, TriEoDon H. WEIN- rLiUs, a citizen of the United States, residing at St. Cloud, in the county of Stearns, State oi" Minnesota, have invented certain new and useful Improvements in rlelephones, of which the following is a specication, reference being had therein to the accompanying drawings.

My invention relates to improvements in telephones of the class known as mechanical telcphones;7 and the object of my improvements is the construction of a device that will increase the eliiciency and the volume and quality of sound transmitted and received by said telephones. l attain these objects by the construction illustrated in the accompanying drawings, in which- Figure 1 is a central section of a telephone constructed in accordance with my invention. Fig. 2 is a perspective view of the diaphragm formed of two thicknesses of parchment, and showing one of the layers as broken away.

The case consists of two parts, A and B, cach composed of a single piece or block of w ood suitably turned, as hereinafter described, between which is stretched and clamped the diaphragm D, consisting of two thicknesses, d d,oi' parchment. r)lie rear part, A, has a large central cavity on both sides, and between these cavities a thin iiat partition is retained to form the sounding-board a. The `front portion of the back block, A, is turned out or recessed at A', adjacent to .its periphery, to form an annular shoulder, A2, adjacent to its central cavity, A, and upon this shoulder the two parchment thicknesses of the diaphragm D are stretched, after having been suitably dampened, by forcing upon their edges the front ring, B, of the case, he rear face of said ring being suitably recessed and shouldered at BZ to correspond and interlock with the annular shoulder and recess upon the back block, A. By this interlocking of the surfaces two circular creases and bends, dL d?, at right angles to each other, are formed in the diaphragm, that eflcctually prevent its relaxation or giving way at the edges. The parts A and B are then united by wood-screws c.

The diaphragnthas a small perforation, di, in the center, for the passage .of the wire E, and

y.upon the 'front thereof is placed the hard-rubing-chamber is produced between the diaphragm and the 'flat sounding-board. A conical funnel or cavity, A", having its smallest end toward said sounding-board, is made in the rear oi' the back block, A, and thus while the volume of sound is intensified the ordinary ringing noise is mostly avoided by having the diaphragm constructed of two thicknesses of the same homogeneous substance having the properties of parchment.

l am aware that diaphragms for telephones have been made of one thickness of parchment combined with one or more thicknesses of wood veneer, and also of two thicknesses of parchment separated by one or more thicknesses of fabric or rubber, and also of one thickness of rawhide, combined with a paper disk, and i do not claim any compounds of this nature.

YVhen it isdcsired to check the humming sound coming over the wire, or to deaden thev sound to all but the operator, the sound-waves are controlled by means of a plunger, F, set radially in the rear block oi' the case behind the sounding-board, and having its outer end projectinglrom said case and provided with a buttomf, that can be pressed upon by the operator. The inner end of the plunger carries a knob, F, covered with felt or other yielding substance, and is adapted to be pressed with more or less force against the transmitting-wire E; but to permit a loud call the plunger is normally maintained away -from the wire by a spring, g, coiled around the plunger and having its outer end bearing against the under side of its button f. A shoulder or collar, fi, is placed upon the plunger and is made to abut against the peripheral wall of thev conical cavity At of the case, to prevent the plunger from springing back too far from the wire.

Having now fully described my invention, l claiml. In combination with the annular blocks ICO secured in juxtaposition, substantially as and 3. In combination with the rear block, A, of for the purpose described. a telephone-case and its wire7 the plunger F,

2. In combination with the fro11tblock,B,of having a yielding knob adapted to bear upon 15 a telephone and the diaphragm consisting of said wire, and a spring to retract it, substantwo disks of the same material stretched in tially as described. the rear thereof, the rear block provided with In testimony whereof I affix my signature a fiat perforated sounding-board having its in presence of two Witnesses. .n sides arallel With the diaphragm and in the l" 1 Y rear 011)" said sounding-board abcohieal cavity THEODOR H' TIDINHAUS' having its small end abutting against said NVitnesses: sounding-board, substantially as and for the g ANDREW C. RoBEa'rsoN, purpose described. W. L. SPOONER. 

